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Geminids meteor shower promises strong showing
BY MARK ARMSTRONG
ASTRONOMY NOW

Posted: 12 December 2013


The Geminids meteor shower is the richest shower of the year, and along with the much lesser Ursids, nicely rounds off the meteor observing season for 2013.


AN graphic by Greg Smye-Rumsby
 
With normal limits of Dec 8-17 the maximum is predicted for the 1am on the night of 13/14 December. The waxing gibbous Moon (81 percent illuminated) will makes its unwelcome presence felt this year some 66 degree away in Aries. It doesn't set until 4.50am and so will interfere with observations for most of the night.

In good conditions the Geminids regularly produce 80 meteors per hour (ZHR 100+) with the radiant, which lies a few degrees north of Castor, highest in the south (67 degrees) at 1am. It's worth observing on the following night, 14/15 December too, as observations tend to suggest many of the brighter events occur some hours after maximum so it's possible the tail-end of this could be observed.

Geminids are relatively slow meteors entering the upper atmosphere at speeds of 35km/s and there are a large proportion of bright, colourful events. The meteoroid stream has spawned from an asteroid - sungrazing (3200) Phaethon - rather than a comet and this seems to make the debris more solid or robust and can survive for longer before burning up. Recent images has actually shown a comet-like tail to Phaethon so it's more appropriate perhaps to term it a 'rock comet.'

The Ursids are active between 17-25 December with the peak occurring on 22-23 December with low rates of at around five meteors per hour. The radiant lies close to the 'bowl' of Ursa Minor in the vicinity of Polaris, the Pole Star. Once the debris stream has been shed by the Ursids parent comet 8P/Tuttle. Once again the Moon will interfere with observations, this time a waning gibbous moon on the Leo/Cancer border that rises at 9.26pm and transits at 3.30am.

As with observing any meteor shower the best advice is not to stare at the actual radiant but at an altitude of 50 degrees (about the same altitude of the Pole Star from the UK) and 30-40 degrees to one side of shower radiant (the width of a fist held at arm's length is about ten degrees). Recent nights have been bone-chilling so be well prepared, especially if you are travelling to a dark site to make your watch. Wrap up well in layers of warm, dry clothing and keeping hands, feet and head warm is essential! Many people just prefer to observe for fun but if you would like to 'do some science,' then check out the advise on the British Astronomical Association's website.

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
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Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
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3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
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